Excited State — Definition, Formula, Properties & Uses | AllChemicals | AllChemicals

Also Known As	Electronic excited state, excited level, upper state (spectroscopy)

What is Excited State?

An energy state of an atom, ion, or molecule that is higher than its ground state. Electrons in excited states occupy higher energy orbitals. When electrons return to lower energy levels, they emit photons of specific wavelengths, producing characteristic emission spectra.

Properties & Characteristics

An excited state is a quantum state of an atom, molecule, or nucleus in which the system has absorbed energy and is at a higher energy level than the ground state. Electronic excited states result from UV-Vis photon absorption (π→π*, n→π* transitions); vibrational and rotational excited states absorb IR and microwave radiation. Excited states have short lifetimes and decay by emitting photons (fluorescence, phosphorescence) or by non-radiative relaxation.

Uses & Applications

Excited states are fundamental to: spectroscopy (UV-Vis, IR, Raman, fluorescence), laser operation (stimulated emission from population-inverted excited states), photosynthesis (excited chlorophyll molecules drive electron transfer), photochemistry (excited state reactivity differs from ground state), and fluorescent labels in biochemistry.

Safety Information

Excited state molecules may react differently and more readily than ground state molecules, potentially generating reactive intermediates (singlet oxygen, radicals). UV photons creating excited states in skin biomolecules can cause DNA damage and sunburn. Photosensitisers that generate long-lived excited triplet states used in PDT can cause tissue damage.

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Key Facts

Term Excited State

Index All "E" terms

Synonyms Electronic excited state, excited level, upper state (spectroscopy)

Frequently Asked Questions

What is Excited State?

An energy state of an atom, ion, or molecule that is higher than its ground state. Electrons in excited states occupy higher energy orbitals. When electrons return to lower energy levels, they emit photons of specific wavelengths, producing characteristic emission spectra.

What is Excited State used for?

Is Excited State hazardous?

More "E" Terms

Effective Collisions Effective Collisions E ≥ Ea (activation energy required) Effective Molality m_eff = i × m (van't Hoff factor) Effective Nuclear Charge Z_eff = Z − σ (Slater's rules) Efflorescence Hydrated salt losing water in air: M·nH₂O(s) → M·(n-x)H₂O(s) + xH₂O(g) Einsteinium Es Electrical Conductivity κ = 1/ρ; Λm = κ/c Electrochemical Cell Galvanic cell: ΔG = −nFE_cell; Electrolytic cell: ΔG = +nFE_applied Electrochemical Series Arranged by E° (standard reduction potential); SHE: E° = 0.00 V Electrochemistry E° cell = E° cathode − E° anode | ΔG° = −nFE° Electrochemistry Electrode

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